Elongated flow stopper in standing valve of bottom hole spring assembly for facilitating production of hydrocarbons

ABSTRACT

A flow stopper for a standing valve within a bottom hole spring assembly for facilitating production of hydrocarbons has an elongated shape. The elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, and the two points of contact are separated by a gap where the flow stopper does not contact the housing. The flow stopper may include a first and a second ball where the balls are connected by a stem. The flow stopper may also include a plurality of balls that are not connected to each other. The flow stopper may include a ball connected to a stem.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of Canadian Application No. 3,042,319 filed May 6, 2019, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION (1) Field of the Invention

The invention pertains generally to a flow stopper in a standing valve within a bottom hole spring assembly for facilitating production of hydrocarbons from a subterranean well. More specifically, the invention pertains to an elongated flow stopper providing a better seal when the standing valve is positioned deeper in the heel of a horizontal well in comparison to a conventional check ball design.

(2) Description of the Related Art

Bottom hole spring assemblies are commonly used in wellbore tubing of vertical and horizontal subterranean wells. The bottom hole spring assembly is used to absorb the shock of a falling plunger. The spring assembly protects the plunger as well as the downhole tubing equipment from damage that may results from the free-falling plunger when there is not enough fluid in the wellbore tubing for dampening. The plunger is part of a plunger lift system used to remove accumulated liquids above the bottom hole spring assembly within the wellbore tubing to thereby restore and/or facilitate gas flow. Conventional bottom hole spring assemblies include a standing valve (also known as a check valve) comprising a check ball that works in conjunction with a seat to allow fluid to rise up though the value above the spring assembly but to trap the fluid and prevent the fluid passage back into the section of the well below the spring assembly.

Although conventional check valves work well in vertical wells, they do not maintain an effective seal when positioned too deep in the heel section of a horizontal well. As the placement depth of the spring assembly is increased in the heel section, the angle of the check valve becomes more and more horizontal and at a certain point the check ball fails to seal properly against the seat. In order to keep the orientation of the check valve closer to vertical and allow an effective seal of ball against seat, the bottom hole spring assembly needs to be positioned closer to the surface in the heel section. Moving the spring assembly closer to the surface reduces the amount of liquid that can be trapped above the spring assembly. Each plunger cycle thus lifts less fluid from the well than would be achieved if the spring assembly were located at a greater depth. Furthermore, the liquid that remains below the spring assembly and is not removed by the plunger hinders hydrocarbon flow to surface.

BRIEF SUMMARY OF THE INVENTION

According to an exemplary embodiment of the invention there is disclosed a flow stopper for a standing valve within a bottom hole spring assembly for facilitating production of hydrocarbons from a subterranean well. The bottom hole spring assembly includes a tubular cavity within a housing. The standing valve prevents backflow of a fluid column to allow a surface controlled plunger system to remove the fluid column. The housing has a plurality of ports providing fluid access to the tubular cavity. The flow stopper is moveable between a first position and a second position within the tubular cavity. The flow stopper in the first position is adjacent to a seat of a bottom port of the ports thereby obstructing fluid flow through the bottom port. The flow stopper in the second position is away from the seat of the bottom port thereby allowing fluid to flow through the bottom port. The flow stopper has an elongated shape, and the elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, and the concave section ensures that the first point of contact and the second point of contact are separated by a gap where the flow stopper does not contact the inner surface of the housing on the line.

According to an exemplary embodiment of the invention there is disclosed a bottom hole spring assembly for facilitating production of hydrocarbons from a subterranean well. The bottom hole spring assembly includes a housing having a plurality of ports providing fluid access to a tubular cavity within the housing. A standing valve has a seat and a flow stopper, and the standing valve prevents backflow of a fluid column to allow a surface controlled plunger system to remove the fluid column. The flow stopper is moveable between a first position and a second position within the tubular cavity. The flow stopper in the first position is adjacent to the seat of a bottom port of the ports thereby obstructing fluid flow through the bottom port. The flow stopper in the second position is away from the seat of the bottom port thereby allowing fluid to flow through the bottom port. The flow stopper has an elongated shape, and the elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line. The concave section ensures that the first point of contact and the second point of contact are separated by a gap where the flow stopper does not contact the inner surface of the housing on the line.

These and other advantages and embodiments of the present invention will no doubt become apparent to those of ordinary skill in the art after reading the following detailed description of preferred embodiments illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof:

FIG. 1 shows an exploded view of a bottom hole spring assembly having a conventional check ball according to the prior art.

FIG. 2 shows a schematic of the bottom hole spring assembly of FIG. 1 placed within the heel section of a horizontal well at a first depth where the check ball can seal properly.

FIG. 3 shows a schematic of the bottom hole spring assembly of FIG. 1 placed within the heel of the horizontal well at a second point which is deeper than the first point of FIG. 2 and prevents the check ball from sealing properly.

FIG. 4 shows a sideview of a flow stopper having two similar size balls connected by a stem according to an exemplary embodiment.

FIG. 5 shows a perspective view of the flow stopper of FIG. 4.

FIG. 6 shows a schematic of the bottom hole spring assembly within the heel of a horizontal well at a second point (similar depth as the second point of FIG. 3) having the flow stopper of FIG. 4 in a first position sealed against the seat according to an exemplary embodiment.

FIG. 7 shows a schematic of the bottom hole spring assembly within the heel of a horizontal well at a second point (similar depth as the second point of FIG. 3) having the flow stopper of FIG. 4 in a second position away from the seat according to an exemplary embodiment.

FIG. 8 shows an exploded view of the bottom hole spring assembly with the flow stopper of FIG. 4 according an exemplary embodiment.

FIG. 9 shows the flow stopper of FIG. 4 in the first position sealed against the seat to restrict fluid flow according to an exemplary embodiment.

FIG. 10 shows the flow stopper of FIG. 4 in a second position away from the seat to allow fluid to flow through a bottom port according to an exemplary embodiment.

FIG. 11 shows the flow stopper of FIG. 4 within the housing of the bottom hole spring assembly according to an exemplary embodiment.

FIG. 12 shows a sideview of a flow stopper having two balls not mechanically connected to each other according to an exemplary embodiment.

FIG. 13 shows a sideview of a flow stopper having three balls not mechanically connected to each other according to an exemplary embodiment.

FIG. 14 shows a sideview of a flow stopper having three balls mechanically connected to each other according to an exemplary embodiment.

FIG. 15 shows a sideview of a flow stopper having a ball connected a stem according to an exemplary embodiment.

FIG. 16 shows a sideview of a flow stopper having two different sized balls connected by a stem according to an exemplary embodiment.

FIG. 17 shows a sideview of a flow stopper having the flow stopper of FIG. 4 with an additional ball connected to a middle portion of the stem according to an exemplary embodiment.

FIG. 18 shows an exploded view of the bottom hole spring assembly having the flow stopper of FIG. 12 according to an exemplary embodiment.

FIG. 19 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 12 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 20 shows an exploded view of the bottom hole spring assembly having the flow stopper of FIG. 13 according to an exemplary embodiment.

FIG. 21 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 13 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 22 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 14 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 23 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 15 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 24 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 16 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 25 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 17 in the first position sealed against the seat to restrict fluid flow according to an exemplary embodiment.

FIG. 26 shows an exploded view of the bottom hole spring assembly incorporating a pressure relief system including the flow stopper of FIG. 4 according an exemplary embodiment.

FIG. 27 shows a closeup exploded view of the bottom hole spring assembly with pressure relief system of FIG. 26.

FIG. 28 shows the flow stopper of FIG. 4 in the first position sealed against the seat while the pressure relief system is opened according to an exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1, FIG. 2, and FIG. 3 provide an overview of conventional standing valves used within a bottom hole spring assembly in order to better describe existing limitations. FIG. 1 shows an exploded view of a bottom hole spring assembly having a conventional check ball according to the prior art. The bottom hole spring assembly 100 includes a conventional standing valve having the conventional check ball 102 working in conjunction with a seat 104 to trap fluid above the spring assembly. The standing valve is designed to prevent fluid passage back through a bottom port of the bottom hole spring assembly and into the formation.

The conventional valve provides an adequate seal in vertical wells where the bottom hole assembly is oriented vertically within the wellbore tubing; however, the use of conventional standing valves is limited within horizontal well. As the bottom hole assembly is placed deeper within the wellbore tubing of a horizontal well, the bottom hole spring assembly approaches a horizontal orientation.

FIG. 2 shows a schematic of the bottom hole spring assembly of FIG. 1 placed within the heel section of a horizontal well at a first depth (point A) where the check ball can seal properly according to the prior art. In this example, at point A the bottom hole spring assembly angle a is 45 degrees, where zero degrees corresponds to a vertical vector pointing directly upwards to the surface. The conventional standing valve check ball used with the bottom hole spring assembly may be able to maintain a seal against the seat when an angle a of the bottom hole spring assembly is less than 48 degrees such as illustrated in FIG. 2. However, it would be advantageous to place the bottom hole spring assembly even deeper into the horizontal well as it would allow more fluid to be captured per plunger cycle.

FIG. 3 shows a schematic of the bottom hole spring assembly of FIG. 1 placed within the heel of the horizontal well at a second point (point B) which is deeper than the first point of FIG. 2 and prevents the check ball from sealing properly. In this example, at point B the bottom hole spring assembly angle β is 65 degrees. When the bottom hole spring assembly is placed at point B, the angle β of the bottom hole spring assembly is greater than a limit angle (e.g., 48 degrees) at which the spring assembly prevents fluid backflow. When the bottom hole spring assembly is placed at angles higher than the limit angle such as illustrated in FIG. 3, the ball is unable to maintain the seal with the seat as the ball rolls out of the seat. As a result, the fluid flows back into the formation via the seat port drastically reducing a height of the fluid column which can be removed per plunger cycle. The backflow of fluid into the formation also impedes the flow of hydrocarbons to the surface. In short, the conventional standing valve design limits the depth at which the standing valve can maintain the seal.

FIG. 4 shows a sideview of a flow stopper having two similar size balls connected by a stem according to an exemplary embodiment. In this embodiment, the flow stopper includes a first ball and a second ball which are connected by a stem. The ball shapes of this embodiment are advantageous to increase the length of the flow stopper while minimizing contact area with the internal cavity of the check valve housing (also known as the check valve cage). Additionally, they are likely to have uniform wear and tear when the flow stopper is exposed to the abrasives.

In this embodiment, the stem of the flow stopper has a cylindrical shape which has a diameter less than the diameter of the balls. The diameter of the stem is designed to be less than the diameter of the balls to ensure the stem does not contact the internal cavity housing of the bottom hole spring assembly while the flow stopper moves within. The first ball and the second ball have diameters greater than a width of slots that act as ports providing fluid access to the tubular cavity in the hollow housing of the bottom hole spring assembly (i.e., check valve cage), which ensures the flow stopper stays within the housing.

FIG. 5 shows a perspective view of the flow stopper of FIG. 4. As shown in FIG. 4 and FIG. 5, when the flow stopper is placed against a straight line 500, the flow stopper has at least two points of contact 502, 504 with the line 500, and the two points 502, 504 of contact are separated by a gap 506 formed by a concave section 508 where the balls curve inward to meet the stem.

FIG. 6 shows a schematic of the bottom hole spring assembly within the heel of a horizontal well at point B (similar depth as the second point—point B—of FIG. 3) having the flow stopper of FIG. 4 in a first position where the stopper is sealed against the seat according to an exemplary embodiment. The flow stopper is moveable between the first (sealed) position shown in FIG. 6 and a second (unsealed) position shown in FIG. 7 within the tubular cavity formed within the housing of the bottom hole spring assembly (i.e., within the check valve cage). The flow stopper in the first position as shown in FIG. 6 is adjacent to the seat of a bottom port thereby restricting fluid flow through the bottom port. The flow stopper in the second position shown in FIG. 7 is away from the seat of the bottom port thereby allowing fluid to flow through the bottom port and into the housing.

The barbell-shaped flow stopper provides the seal in the first position at greater angles compared to the convention ball valve due to its longer length and higher mass. The second ball contacts the seat rim in the first position to maintain the seal around the seat rim and prevents the flow stopper from sliding, rolling or otherwise moving out of the seat.

By enabling a good stopper seal at higher angles β, the flow stopper of this embodiment enables placing the bottom hole spring assembly deeper into the wellbore tubing. Additional fluid may beneficially be removed per plunger cycle in comparison to placing the spring assembly at point A closer to the surface; the extra fluid removed is between points A and B. In some embodiments, the barbell shape of the flow stopper makes it possible to hold fluid in wellbore tubing of angles β upwards of 76 degrees compared to the 48 degrees achieved with the conventional ball valve.

Beneficially, the prior art circular check ball can easily be replaced with the barbell-shaped flow stopper of FIG. 4 without modifying anything else of the bottom hole spring assembly. The concave section of the flow stopper helps ensure that there is a point of contact along the housing wall above the seat to hold the lower ball against the seat while ensuring the flow stopper is not jammed in a fixed position within the cavity.

FIG. 7 shows a schematic of the bottom hole spring assembly within the heel of a horizontal well at a second point (similar depth as the point B of FIG. 3) having the flow stopper of FIG. 4 in a second position where it is away from the seat according to an exemplary embodiment.

When the flow stopper is dislodged from the seat, the momentum from additional mass allows the flow stopper to fall into the seat at greater angle compared to the conventional check ball after the fluid flow through the bottom port has stopped.

As illustrated, the flow stopper has an elongated shape, and the elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, the concave section ensures that the first point of contact and the second point of contact are separated by a gap where the flow stopper does not contact the inner surface of the housing on the line. The concave section is formed between the two balls in this embodiment.

Tolerances between the flow stopper and the tubular cavity of the housing may be adjusted to be close but not snug as the bottom hole spring assembly is often exposed to sand and other debris which may hinder the flow stopper movement within the cavity. By having adequate tolerances, the flow stopper may move freely within the housing to allow or restrict flow depending on its position. The two points of contact of each ball of the barbell shape help reduce the friction and allow for movement between the sealed and unsealed positions.

FIG. 8 shows an exploded view of the bottom hole spring assembly with the flow stopper of FIG. 4 according an exemplary embodiment.

FIG. 9 shows the flow stopper of FIG. 4 in the first position sealed against the seat to restrict fluid flow according to an exemplary embodiment.

FIG. 10 shows the flow stopper of FIG. 4 in a second position away from the seat to allow fluid to flow through a bottom port according to an exemplary embodiment.

FIG. 11 shows the flow stopper of FIG. 4 within the housing of the bottom hole spring assembly according to an exemplary embodiment.

FIG. 12 shows a sideview of a flow stopper having two balls according to an exemplary embodiment. In this embodiment, the balls are not mechanically connected to each other and are free to separately roll and move within the housing. The first ball makes a first point of contact on the line and the second ball make a second point of contact on the line. When the balls are physically touching which happens as a result of gravity pulling both balls toward the seat, a concave section is formed between the two points of contact along the housing line which are separated by a gap. In this way, similar to the barbell shaped flow stopper, utilizing two check balls instead of one can also achieve a similar elongated flow stopper shape with concave section C. Although the above example described the balls being not mechanically connected, in another embodiment, they may be connected together and not independent parts.

FIG. 13 shows a sideview of a flow stopper having three balls according to an exemplary embodiment. Again, the three balls in this embodiment are not mechanically connected to each other and are free to roll within the housing. The first ball makes a first point of contact on the line, the second ball make a second point of contact on the line, and the third ball makes a third point of contact on the line. When the three ball are touching, the balls form two gaps between the three points of contact. The first gap is formed between the first ball and the second ball, and the second gap is formed between the second ball and the third ball. Each of the gap has a concave section C similar to as described above. Similar benefits are achieve as above because of the increased weight allowing a great angle β while ensuring minimal friction of the flow stopper balls within the housing. Again, in another embodiment, the three balls of the flow stopper may be attached to one another. Any number of balls, either attached or unattached may be utilized to form the flow stopper in other embodiments.

FIG. 14 shows a sideview of a flow stopper having three balls mechanically connected to each other according to an exemplary embodiment. In this embodiment, three balls are mechanically connected to each other so they together can slide within the housing between the first position and the second position. The first ball and the third ball have the same diameter, and a diameter of the second ball is smaller than the first and the third ball diameter. The first ball makes a first point of contact on the line and a third ball make a second point of contact on the line. The two points of contact are separated by a gap which forms a concave section C.

FIG. 15 shows a sideview of a flow stopper having a ball connected a stem according to an exemplary embodiment. The ball is connected to a first end of a cylindrical stem, and the second end of the stem is rounded. A stem diameter and the first ball diameter are greater than a width of the slots within the housing. The first ball makes a first point of contact on the line and the stem makes a second point of contact on the line. A concave section C is formed between the two points of contact on a line. The first and the second point of contact are separated by a gap where the flow stopper does not contact the housing.

FIG. 16 shows a sideview of a flow stopper having two different sized balls connected by a stem according to an exemplary embodiment. The first ball diameter and the second ball diameter are greater than a diameter of the stem. The first ball makes a first point of contact on the line and a second ball make a second point of contact on the line. The first and the second point of contact are separated by a gap formed by a concave section C where the flow stopper does not contact the housing.

FIG. 17 shows a sideview of a flow stopper having the flow stopper of FIG. 4 with an additional ball connected to a middle portion of the stem according to an exemplary embodiment. In this embodiment, the flow stopper has a longer length compared to the barbell flow stopper illustrated in FIG. 4 and FIG. 16. The modified barbell comprises a first ball, a second ball, a third ball, a first stem, and a second stem. The first ball and the second ball are connected by the first stem, and the second ball and the third ball are connected by a second stem. The first ball makes a first point of contact and the third ball makes a second point of contact on the line. A concave section C is formed between the first contact point and the second contact point, and the two points of contact are separated by a space. The second ball provides additional mass to the flow stopper without creating additional friction between the flow stopper and the housing. In some embodiment, the first and the third balls have different diameters, and the first and second stem have different diameters.

FIG. 18 shows an exploded view of the bottom hole spring assembly having the flow stopper of FIG. 12 formed by two independent check balls according to an exemplary embodiment. In some embodiments, the two balls have different diameters. In some embodiments, the same check balls as the prior-art can be utilized making for easy enhancement of a conventional check valve for use in a horizontal well by simply adding two check balls instead one. There may beneficially be no need for additional manufacturing set-ups and, if a ball gets damaged, it can be easily replaced with existing supplies.

FIG. 19 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 12 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment. In some embodiments, the additional mass and length of the two balls allows the standing valve configured with two balls to provide the seal up to a bottom hole spring assembly angle β of approximately 57 degrees.

FIG. 20 shows an exploded view of the bottom hole spring assembly having the flow stopper of FIG. 13 according to an exemplary embodiment. In some embodiments, the three balls have different diameters.

FIG. 21 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 13 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment. In some embodiments, the additional mass and length provided by three balls allows the standing valve configured with three balls to provide the seal up to a bottom hole spring assembly angle β of approximately 66 degrees. Three balls generally receive the same benefits as two balls but achieve higher angles β due to the additional mass of the third ball.

FIG. 22 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 14 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment. Since the second ball has a smaller diameter, the second ball does not contact the housing reducing the contact area and therefore reducing friction between the flow stopper and the housing.

FIG. 23 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 15 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 24 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 16 in the first position sealed against the seat to restrict fluid flow according an exemplary embodiment.

FIG. 25 shows a schematic of the bottom hole spring assembly having the flow stopper of FIG. 17 in the first position sealed against the seat to restrict fluid flow according to an exemplary embodiment.

TABLE 1 Flow stopper configuration and the corresponding angle of effectiveness in some embodiments with respect to the vertical orientation Flow Stopper Configuration Angle of effectiveness (degrees) One ball 48 Two balls 57 Three balls 66 Barbell shape 76

According to an exemplary embodiment there is a flow stopper for a standing valve within a bottom hole spring assembly for facilitating production of hydrocarbons. The flow stopper has an elongated shape. The elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, and the two points of contact are separated by a gap where the flow stopper does not contact the housing. The flow stopper may include a first and a second ball where the balls are connected by a stem. The flow stopper may include a plurality of balls that are not connected to each other. The flow stopper may include a ball connected to a stem.

Although the invention has been described in connection with preferred embodiments, it should be understood that various modifications, additions and alterations may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention.

For instance, in some embodiments it is desirable to not have a perfect seal between the flow stopper and the seat to permit the fluid to flow back into the formation which reduces the likelihood of needing a wireline truck to pull the plunger. In this way, the flow stopper balls or ends may have notches carved therein to provide for some limited fluid flow even while the flow stopper is against the seat.

Use of the balls and rounded bulges similar to balls on ends of the elongated flow stopper reduces a contact area between the flow stopper and the housing as balls typically have smaller contact area within a tubular cavity in comparison to cylinders, ellipsoids, ovoid, etc. As the contact area is reduced, the friction between the housing and the flow stopper is also reduced making it easier for the flow stopper to slide within the housing. That said, it is possible to use other shapes on the ends of the elongated flow stopper such triangular prisms and shapes, rectangular shapes, pyramid shapes, etc.; however, the subterranean well environment tends to be abrasive with sand and such non-rounded shapes may experience uneven wear and tear at the edges and the ability of the flow stopper to provide the seal may be impacted. In some embodiments, the first ball and the second ball may have an ovoid shape or any other shape capable of providing a seal. Other shapes that may be utilized include a cube, a pyramid, a rectangular prism, a triangular prism, or a combination thereof, for example.

As described above, flow stoppers utilized here are particularly beneficial with a standing valve. In some embodiments, the standing valve is a pressure relief standing valve which further includes a spring.

FIG. 26, FIG. 27, and FIG. 28 illustrate a pressure relief system that utilizes the barbell-shaped flow stopper of FIG. 4 according to an exemplary embodiment. In some embodiments, the bottom hole spring assembly is converted to a pressure relief system by the use of a pressure relief kit. The kit consists of a spring and seat. The seat shoulders out to a lip inside the cage area where it mechanically seals. When assembled, there is slight tension on the spring. The pressure relief standing valve is used to trap fluids, and it can also be used to release the fluids back to the formation. The pressure relief valve operates under a pressure differential that is activated by the weight of the fluid column coupled with an applied back pressure. Once the pressure differential is reached, the relief valve opens due to the tension on the spring to allow fluids to be recycled back into the formation and limit the need for wire line or swab rig recovery. In some embodiments, the flow stopper is used with a pressure relief standing valve.

Although the above description has described benefits of the elongated flow stopper with concave section to facilitate hydrocarbon production from a subterranean well, other applications including applications outside of the oil and gas industry may also benefit from having a check valve that works at angles β closer to horizontal and may therefore employ elongated flow stoppers described herein in a similar manner.

The flow stoppers described herein are made of metals such as titanium and stainless steel in some embodiments. Other examples of materials that are used to form the flow stoppers in some embodiments include Cobalt, Chrome, Carbide, Tungsten Carbide, Titanium Carbide, and any other alloy or non alloy. In yet other embodiments, the flow stopper is made from any ferrous or non-ferrous material. Tough plastic materials are also be utilized for forming the flow stopper in some embodiments.

All combinations and permutations of the above described features and embodiments may be utilized in conjunction with the invention. 

What is claimed is:
 1. A flow stopper for a standing valve within a bottom hole spring assembly for facilitating production of hydrocarbons from a subterranean well, the bottom hole spring assembly including a tubular cavity within a housing wherein the standing valve prevents backflow of a fluid column to allow a surface controlled plunger system to remove the fluid column, the housing having a plurality of ports providing fluid access to the tubular cavity, wherein: the flow stopper is moveable between a first position and a second position within the tubular cavity; the flow stopper in the first position is adjacent to a seat of a bottom port of the ports thereby obstructing fluid flow through the bottom port; the flow stopper in the second position is away from the seat of the bottom port thereby allowing fluid to flow through the bottom port; the flow stopper has an elongated shape; and the elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity, the concave section allowing the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, the concave section ensuring that the first point of contact and the second point of contact are separated by a gap where the flow stopper does not contact the inner surface of the housing on the line.
 2. The flow stopper of claim 1, comprising: a first ball; and a stem connecting a first end of the stem to the first ball.
 3. The flow stopper of claim 2, wherein a second end of the stem is rounded.
 4. The flow stopper of claim 1, comprising: a first ball; a second ball; and a stem coupling the first ball to the second ball.
 5. The flow stopper of claim 4, wherein a thickness of the stem is smaller than a diameter of the first ball.
 6. The flow stopper of claim 5, wherein the thickness of the stem is smaller than a diameter of the second ball.
 7. The flow stopper of claim 4, wherein diameters of the first ball and the second ball are larger than a width of slots in the housing of the bottom hole spring assembly.
 8. The flow stopper of claim 1, comprising a plurality of balls.
 9. The flow stopper of claim 8, wherein the balls are not mechanically connected to each other and are therefore free to separately move within the tubular cavity.
 10. The flow stopper of claim 8, wherein a diameter of a first ball is different from a diameter of a second ball.
 11. The flow stopper of claim 8, wherein the balls are connected by one or more stems.
 12. The flow stopper of claim 1, wherein the flow stopper is an integral component.
 13. The flow stopper of claim 1, wherein the flow stopper comprises a plurality of stopper parts that are not mechanically connected to each other and are therefore free to separately move within the tubular cavity.
 14. The flow stopper of claim 1, wherein the flow stopper is fabricated from stainless steel.
 15. The flow stopper of claim 1, wherein the flow stopper is fabricated from titanium.
 16. A bottom hole spring assembly for facilitating production of hydrocarbons from a subterranean well, the bottom hole spring assembly comprising: a housing having a plurality of ports providing fluid access to a tubular cavity within the housing; and a standing valve comprising a seat and a flow stopper, the standing valve prevents backflow of a fluid column to allow a surface controlled plunger system to remove the fluid column; wherein the flow stopper is moveable between a first position and a second position within the tubular cavity; the flow stopper in the first position is adjacent to the seat of a bottom port of the ports thereby obstructing fluid flow through the bottom port; the flow stopper in the second position is away from the seat of the bottom port thereby allowing fluid to flow through the bottom port; the flow stopper has an elongated shape; and the elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of the housing in a lengthwise direction of the tubular cavity, the concave section allowing the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, the concave section ensuring that the first point of contact and the second point of contact are separated by a gap where the flow stopper does not contact the inner surface of the housing on the line.
 17. The bottom hole spring assembly of claim 16, wherein the flow stopper includes a first ball and a stem connecting a first end of the stem to the first ball.
 18. The bottom hole spring assembly of claim 16, wherein: the flow stopper includes a first ball, a second ball, and a stem connecting the first ball to the second ball; a diameter of the first ball is substantially equal to a diameter of the second ball; and the stem has a cylindrical shape which has a diameter less than diameters of the first ball and the second ball.
 19. The bottom hole spring assembly of claim 16, wherein the flow stopper comprises a plurality of stopper parts that are not mechanically connected to each other and are therefore free to separately move within the tubular cavity.
 20. The bottom hole spring assembly of claim 19, wherein the plurality of stopper parts comprises a plurality of balls. 